Exodus 31:14-16

Young's Literal Translation

¹⁴ and ye have kept the sabbath, for it [is] holy to you, he who is polluting it is certainly put to death -- for any who doeth work in it -- that person hath even been cut off from the midst of his people.

¹⁵ `Six days is work done, and in the seventh day [is] a sabbath of holy rest to Jehovah; any who doeth work in the sabbath-day is certainly put to death,

¹⁶ and the sons of Israel have observed the sabbath; to keep the sabbath to their generations [is] a covenant age-during,